As is commonly known, a wastegate valve is a type of control valve provided on a bypass passage for engine exhaust gas in a supercharger, and is for adjusting a supercharging pressure of combustion air supplied to an engine. A wastegate valve control device for a supercharger-equipped internal combustion engine disclosed in Patent Literature 1 below controls an air bypass valve when an abnormality occurs in a drive mechanism for a wastegate valve, and thereby copes with the abnormality. That is, when the abnormality occurs in the drive mechanism for the wastegate valve, the wastegate valve communicates with the air bypass passage, and thereby the wastegate valve control device suppresses an abnormal rise in the supercharging pressure.